The present invention is, broadly, a hand-operated vacuum pump and more specifically, a hand-held and hand-operated vacuum pump for obstetrical use incorporating an improved vacuum regulation system.
For several reasons, hand-held vacuum pumps have, in recent years, come to be more widely used than heretofore in delivery rooms. Chief among these is to assist, in combination with a cranial vacuum bell, in a difficult birth, whereby the assisting physician can more easily maneuver the baby's head, without resort to forceps, to better present it for an easier birth, and perhaps gently exert withdrawal pressure thereon, with greatly reduced chances of injury thereto. One reason for this is the greater control hand-held vacuum pumps give over the degree of vacuum obtainable, as contrasted with vacuum systems generally available in hospitals. Other reasons include providing a means of removing obstetrical fluids for later use and to remove particulate matter therefrom.
However, there are hazards associated with the use of cranial vacuum bells. The vacuum can be applied to the scalp of an unborn child only for a very limited period without injury thereto, and the times of use are cumulative. Unless the birthing can be accomplished in that period, the use of the vacuum cup must be terminated. Several problems can extend the time of use dangerously, among them being leaks in the vacuum system, caused by particulate matter being drawn into the pump mechanism. Further, vacuum relief valves which reduce the vacuum to zero, require precious time to restore it to its useful levels.
Typical of existing hand-held vacuum pumps is that disclosed by Neward U.S. Pat. No. 3,612,722. Air from the space to be exhausted, typically that defined by the baby's scalp and the cranial bell fitted thereon, enters directly through intermediate passages into the pump cylinder. Particulate matter entrapped in this air could affect any or all of the vacuum gauge, the vacuum relief valve, the vacuum pump mechanism, or the pump exhaust valve. Further, the vacuum release or adjustment valve is a rotary valve, and must be manually operated by thumb and forefinger of the physician. This manually operated vacuum release design requires the physician to use both hands to operate the pump and simultaneously adjust the vacuum, whereas it may be more important for the physician to have a free hand for other purposes connected with the birthing process.
In Williams U.S. Pat. No. 4,565,506, a hand-operated vacuum pump is provided which includes a cylinder, head assembly, and elastic seal member. The cylinder and head assembly define opposing grooves, and the elastic seal member is positioned in the grooves to secure the head assembly to the cylinder. A piston assembly is operative within the cylinder to draw a vacuum within the head assembly. Pump also includes a manually operated vacuum relief valve which is normally maintained in the closed position. The manually operated vacuum relief valve may be opened by depression of a manual release pin. However, as in the above-described Neward patent, this requires the use of both hands to operate the pump and simultaneously adjust the vacuum.
Finally, Neward U.S. Pat. No. 4,806,084 also describes a hand-held vacuum pump including a manually operated vacuum relief valve system. The vacuum release mechanism is said to be operable with a finger of the hand about the handle. However, a careful examination of the distance from the handle 102 to the relief valve mechanism 400 raises doubts as to ability of a physician to maintain a grip on handle 102 while manually operating relief valve mechanism 400.